Question on crossovers....

OK...I'm wanting to build a cabinet...and I need a 4 ohm crossover...with tweeter protection...and I don't know if the Carvin Crossover would do it...I'm wanting to start design on a 6x10...for future reference this is to be built later...All I need to know is will the Carvin, which says 600W @ 8Ohms work for a 6x10...And would the speaker impedance matter to make 8Ohms?Or would it change the impedance?

If you use a crossover with another impedance than it was designed for, you'll change the crossover frequency. If you are willing to live with that, fine. But woofers and tweeters MUST have the same impedance (or the same ratio, if the XO has different impedance outputs), or else the XO freq changes differently for both, leaving a hole in the freq response or a big hump in the high-mid range. Sounds terrible.

Actually, if it's more than a first-order crossover (and most are second-order or higher), then using the wrong impedance speaker won't even just move the crossover frequency - it'll result in something really useless.

This is because the frequencies move in different directions for the cap and the inductor when the load impedance changes. If you take a 2nd-order Low-pass for an 8-ohm woofer, and hook it up to a 4-ohm woofer, the coil starts rolling off at half the original frequency, but the cap doesn't start affecting the signal until twice the original (I could have that backwards but you get the idea).